The drug, desvenlafaxine, controlled moderate to severe hot flashes in 62 percent of the women who took it for 12 weeks, as opposed to just 38 percent of women taking a placebo, says researcher JoAnn Pinkerton, M.D., a professor of obstetrics and gynecology and director of the Midlife Health Center at the University of Virginia.

The antidepressant was introduced in 2008 under the brand-name Pristiq, and the petition to label the drug for use in reducing hot flashes is pending before the Food and Drug Administration, she says.

"To me as a clinician this is really exciting, because I need to have some options for women who can't take estrogen or who choose not to take it," Pinkerton says. "To have something that's FDA-approved will be incredibly helpful."

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The findings were presented earlier this month at the annual clinical meeting of the American Congress of Obstetricians and Gynecologists.

Pinkerton and her colleagues evaluated 365 women in a multi-center study supported by drug manufacturer Pfizer. The women, whose average age was 54, had to have experienced at least seven hot flashes a day or 50 per week in order to participate.

After 12 weeks, the women taking Pristiq saw their symptoms reduced by 62 percent, while those on placebos saw a 38 percent reduction in symptoms, Pinkerton reported. She says the researchers chose to study the women with the most intense symptoms, because if the medication could help them, it would most likely help others.

Estrogen remains the "gold standard" for treating hot flashes in women without a uterus, while an estrogen-progesterone combination is often prescribed for women with an intact uterus, Pinkerton says. But doctors try to avoid prescribing hormones to women with a prior history of breast cancer. Large studies have found estrogen-progestin use increases chances of breast cancer, heart disease, stroke and blood clots.

Doctors believe the antidepressants can reset the mechanism in the brain that regulates body temperature.

In 1998, Charles Loprinzi, M.D., a medical oncologist at the Mayo Clinic looking for a safe alternative for his breast cancer patients, conducted a pilot study of a chemical cousin of Pristiq called venlafaxine (Effexor) and found it could reduce hot flashes. Studies have since shown that other antidepressants, such as paroxetine (Paxil) and citalopram (Celexa), have a similar effect, he says.

Pinkerton's study is in line with this research, Loprinzi says. "The results as I see them are similar to what has been seen with venlafaxine," he says.

It isn't the drugs' antidepressant activity that is suppressing the hot flashes, Loprinzi says. Many women see their symptoms decrease within a few days, long before the antidepressant effect is usually felt.

Doctors believe the antidepressants can reset the mechanism in the brain that regulates body temperature.

Pinkerton meanwhile predicts that as more boomers enter menopause "a substantial number of women" will want to discuss the possibility of using low-dose antidepressants to treat hot flashes.